This invention relates to a refrigerant compressor and, more particularly, to a refrigerant compressor having a multi-speed drive motor therein and incorporating vibration dampening bearing means for minimizing vibration of the drive shaft particularly during low speed operation and high speed operation and starting up at high speed and low speed, thereby preventing rubbing between the rotor secured to and driving the drive shaft and the fixed stator of the drive motor.
A recent advance in refrigerant compressors has been the two-speed refrigerant compressor. Such compressor includes a two-speed electric motor operable at a high speed and at a low speed, thereby providing capacity control and economy of operation. In larger compressors of the two-speed type, there is sufficient mass in the drive shaft to minimize the vibration. It has been found, however, in some smaller sized refrigeration compressors, where the drive shaft extends above the upper bearing, the portion above the upper bearing will sometimes deflect and thereby vibrate during low speed operation or high speed operation, as well as starting at both speed of the refrigerant compressor so as to cause rubbing or contact between the rotor carried on the upper portion of the drive shaft and the stator which is fixed to the compressor mechanism. This particular problem is accentuated in single phase two-speed compressors in the smaller sized ranges. The precise cause of the problem is not known at this time, though it is recognized that the problem does exist in a lesser form in larger multi-speed compressors, where the crankshaft or drive shaft is stiffer in relation to its size.
An object of the present invention is to provide an improved multi-speed refrigerant compressor incorporating vibration dampening bearing means for the upper end of the drive shaft so as to prevent rubbing between the rotor carried on the upper portion of the drive shaft and the fixed stator during low speed and high speed operation, as well as start up operations at both speeds.
Another object of the present invention is to provide an improved refrigerant compressor of the two-speed type, wherein an end of the drive shaft may deflect in use, for example during low and high speed operation, switching from high to low speed, or vice versa, and at start up at low or high speed modes of operation, with vibration dampening means on the stator cooperating with the end of the drive shaft so as to eliminate rubbing between the stator and the rotor.
Yet another object of this invention is to provide an improved two-speed refrigerant compressor having a drive shaft subject to deflection at one end during use with a self-aligning vibration dampening bearing fixed relative to the stator and journalling the said one end of the drive shaft so as to prevent the undesirable deflection thereof in use.
A feature of this invention is the provision in a multi-speed refrigerant compressor, e.g., a two-speed refrigerant compressor, comprising compression mechanism, cylinder means in said compression mechanism, piston means in said cylinder means, a drive shaft for actuating the piston means, an electric drive motor including a stator and a rotor electrically coupled thereto, said rotor being connected to said drive shaft for rotating the drive shaft, bearing means for journalling the drive shaft, and vibration dampening means on the side of the motor opposite the bearing means for engaging the drive shaft and preventing undesirable vibration thereof that could cause rubbing between the stator and the rotor during operation of the multi-speed motor.
Other objects, advantages and features of the present invention will be made more apparent in the specification which follows.